/*
 * Copyright (c) 2019, NVIDIA CORPORATION. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef TENSORRT_COMMON__LOGGER_HPP_
#define TENSORRT_COMMON__LOGGER_HPP_

#include "NvInferRuntimeCommon.h"

#include <cassert>
#include <ctime>
#include <iomanip>
#include <iostream>
#include <ostream>
#include <sstream>
#include <string>

namespace tensorrt_common
{
using Severity = nvinfer1::ILogger::Severity;

class LogStreamConsumerBuffer : public std::stringbuf
{
public:
  LogStreamConsumerBuffer(std::ostream & stream, const std::string & prefix, bool shouldLog)
  : mOutput(stream), mPrefix(prefix), mShouldLog(shouldLog)
  {
  }

  LogStreamConsumerBuffer(LogStreamConsumerBuffer && other) : mOutput(other.mOutput) {}

  ~LogStreamConsumerBuffer()
  {
    // std::streambuf::pbase() gives a pointer to the beginning of the buffered part of the output
    // sequence std::streambuf::pptr() gives a pointer to the current position of the output
    // sequence if the pointer to the beginning is not equal to the pointer to the current position,
    // call putOutput() to log the output to the stream
    if (pbase() != pptr()) {
      putOutput();
    }
  }

  // synchronizes the stream buffer and returns 0 on success
  // synchronizing the stream buffer consists of inserting the buffer contents into the stream,
  // resetting the buffer and flushing the stream
  virtual int sync()
  {
    putOutput();
    return 0;
  }

  void putOutput()
  {
    if (mShouldLog) {
      // prepend timestamp
      // std::time_t timestamp = std::time(nullptr);
      // tm* tm_local = std::localtime(&timestamp);
      mOutput << mPrefix << str();
      // set the buffer to empty
      str("");
      // flush the stream
      mOutput.flush();
    }
  }

  void setShouldLog(bool shouldLog) { mShouldLog = shouldLog; }

private:
  std::ostream & mOutput;
  std::string mPrefix;
  bool mShouldLog;
};

//!
//! \class LogStreamConsumerBase
//! \brief Convenience object used to initialize LogStreamConsumerBuffer before std::ostream in
//! LogStreamConsumer
//!
class LogStreamConsumerBase
{
public:
  LogStreamConsumerBase(std::ostream & stream, const std::string & prefix, bool shouldLog)
  : mBuffer(stream, prefix, shouldLog)
  {
  }

protected:
  LogStreamConsumerBuffer mBuffer;
};

//!
//! \class LogStreamConsumer
//! \brief Convenience object used to facilitate use of C++ stream syntax when logging messages.
//!  Order of base classes is LogStreamConsumerBase and then std::ostream.
//!  This is because the LogStreamConsumerBase class is used to initialize the
//!  LogStreamConsumerBuffer member field in LogStreamConsumer and then the address of the buffer is
//!  passed to std::ostream. This is necessary to prevent the address of an uninitialized buffer
//!  from being passed to std::ostream. Please do not change the order of the parent classes.
//!
class LogStreamConsumer : protected LogStreamConsumerBase, public std::ostream
{
public:
  //! \brief Creates a LogStreamConsumer which logs messages with level severity.
  //!  Reportable severity determines if the messages are severe enough to be logged.
  LogStreamConsumer(Severity reportableSeverity, Severity severity)
  : LogStreamConsumerBase(
      severityOstream(severity), severityPrefix(severity), severity <= reportableSeverity),
    std::ostream(&mBuffer)  // links the stream buffer with the stream
    ,
    mShouldLog(severity <= reportableSeverity),
    mSeverity(severity)
  {
  }

  LogStreamConsumer(LogStreamConsumer && other)
  : LogStreamConsumerBase(
      severityOstream(other.mSeverity), severityPrefix(other.mSeverity), other.mShouldLog),
    std::ostream(&mBuffer)  // links the stream buffer with the stream
    ,
    mShouldLog(other.mShouldLog),
    mSeverity(other.mSeverity)
  {
  }

  void setReportableSeverity(Severity reportableSeverity)
  {
    mShouldLog = mSeverity <= reportableSeverity;
    mBuffer.setShouldLog(mShouldLog);
  }

private:
  static std::ostream & severityOstream(Severity severity)
  {
    return severity >= Severity::kINFO ? std::cout : std::cerr;
  }

  static std::string severityPrefix(Severity severity)
  {
    switch (severity) {
      case Severity::kINTERNAL_ERROR:
        return "[F] ";
      case Severity::kERROR:
        return "[E] ";
      case Severity::kWARNING:
        return "[W] ";
      case Severity::kINFO:
        return "[I] ";
      case Severity::kVERBOSE:
        return "[V] ";
      default:
        assert(0);
        return "";
    }
  }

  bool mShouldLog;
  Severity mSeverity;
};

//! \class Logger
//!
//! \brief Class which manages logging of TensorRT tools and samples
//!
//! \details This class provides a common interface for TensorRT tools and samples to log
//! information to the console, and supports logging two types of messages:
//!
//! - Debugging messages with an associated severity (info, warning, error, or internal error/fatal)
//! - Test pass/fail messages
//!
//! The advantage of having all samples use this class for logging as opposed to emitting directly
//! to stdout/stderr is that the logic for controlling the verbosity and formatting of sample output
//! is centralized in one location.
//!
//! In the future, this class could be extended to support dumping test results to a file in some
//! standard format (for example, JUnit XML), and providing additional metadata (e.g. timing the
//! duration of a test run).
//!
//! TODO: For backwards compatibility with existing samples, this class inherits directly from the
//! nvinfer1::ILogger interface, which is problematic since there isn't a clean separation between
//! messages coming from the TensorRT library and messages coming from the sample.
//!
//! In the future (once all samples are updated to use Logger::getTRTLogger() to access the ILogger)
//! we can refactor the class to eliminate the inheritance and instead make the nvinfer1::ILogger
//! implementation a member of the Logger object.

class Logger : public nvinfer1::ILogger  // NOLINT
{
public:
  //  Logger(Severity severity = Severity::kWARNING)
  //  Logger(Severity severity = Severity::kVERBOSE)
  explicit Logger(Severity severity = Severity::kINFO) : mReportableSeverity(severity) {}

  //!
  //! \enum TestResult
  //! \brief Represents the state of a given test
  //!
  enum class TestResult {
    kRUNNING,  //!< The test is running
    kPASSED,   //!< The test passed
    kFAILED,   //!< The test failed
    kWAIVED    //!< The test was waived
  };

  //!
  //! \brief Forward-compatible method for retrieving the nvinfer::ILogger associated with this
  //! Logger \return The nvinfer1::ILogger associated with this Logger
  //!
  //! TODO Once all samples are updated to use this method to register the logger with TensorRT,
  //! we can eliminate the inheritance of Logger from ILogger
  //!
  nvinfer1::ILogger & getTRTLogger()
  {
    printf("verbose\n");
    return *this;
  }

  //!
  //! \brief Implementation of the nvinfer1::ILogger::log() virtual method
  //!
  //! Note samples should not be calling this function directly; it will eventually go away once we
  //! eliminate the inheritance from nvinfer1::ILogger
  //!
  void log(Severity severity, const char * msg) noexcept override
  {
    LogStreamConsumer(mReportableSeverity, severity) << "[TRT] " << std::string(msg) << std::endl;
  }

  //!
  //! \brief Method for controlling the verbosity of logging output
  //!
  //! \param severity The logger will only emit messages that have severity of this level or higher.
  //!
  void setReportableSeverity(Severity severity) { mReportableSeverity = severity; }

  //!
  //! \brief Opaque handle that holds logging information for a particular test
  //!
  //! This object is an opaque handle to information used by the Logger to print test results.
  //! The sample must call Logger::defineTest() in order to obtain a TestAtom that can be used
  //! with Logger::reportTest{Start,End}().
  //!
  class TestAtom
  {
  public:
    TestAtom(TestAtom &&) = default;

  private:
    friend class Logger;

    TestAtom(bool started, const std::string & name, const std::string & cmdline)
    : mStarted(started), mName(name), mCmdline(cmdline)
    {
    }

    bool mStarted;
    std::string mName;
    std::string mCmdline;
  };

  //!
  //! \brief Define a test for logging
  //!
  //! \param[in] name The name of the test.  This should be a string starting with
  //!                  "TensorRT" and containing dot-separated strings containing
  //!                  the characters [A-Za-z0-9_].
  //!                  For example, "TensorRT.sample_googlenet"
  //! \param[in] cmdline The command line used to reproduce the test
  //
  //! \return a TestAtom that can be used in Logger::reportTest{Start,End}().
  //!
  static TestAtom defineTest(const std::string & name, const std::string & cmdline)
  {
    return TestAtom(false, name, cmdline);
  }

  //!
  //! \brief A convenience overloaded version of defineTest() that accepts an array of command-line
  //! arguments
  //!        as input
  //!
  //! \param[in] name The name of the test
  //! \param[in] argc The number of command-line arguments
  //! \param[in] argv The array of command-line arguments (given as C strings)
  //!
  //! \return a TestAtom that can be used in Logger::reportTest{Start,End}().
  static TestAtom defineTest(const std::string & name, int argc, char const * const * argv)
  {
    auto cmdline = genCmdlineString(argc, argv);
    return defineTest(name, cmdline);
  }

  //!
  //! \brief Report that a test has started.
  //!
  //! \pre reportTestStart() has not been called yet for the given testAtom
  //!
  //! \param[in] testAtom The handle to the test that has started
  //!
  static void reportTestStart(TestAtom & testAtom)
  {
    reportTestResult(testAtom, TestResult::kRUNNING);
    assert(!testAtom.mStarted);
    testAtom.mStarted = true;
  }

  //!
  //! \brief Report that a test has ended.
  //!
  //! \pre reportTestStart() has been called for the given testAtom
  //!
  //! \param[in] testAtom The handle to the test that has ended
  //! \param[in] result The result of the test. Should be one of TestResult::kPASSED,
  //!                   TestResult::kFAILED, TestResult::kWAIVED
  //!
  static void reportTestEnd(const TestAtom & testAtom, TestResult result)
  {
    assert(result != TestResult::kRUNNING);
    assert(testAtom.mStarted);
    reportTestResult(testAtom, result);
  }

  static int reportPass(const TestAtom & testAtom)
  {
    reportTestEnd(testAtom, TestResult::kPASSED);
    return EXIT_SUCCESS;
  }

  static int reportFail(const TestAtom & testAtom)
  {
    reportTestEnd(testAtom, TestResult::kFAILED);
    return EXIT_FAILURE;
  }

  static int reportWaive(const TestAtom & testAtom)
  {
    reportTestEnd(testAtom, TestResult::kWAIVED);
    return EXIT_SUCCESS;
  }

  static int reportTest(const TestAtom & testAtom, bool pass)
  {
    return pass ? reportPass(testAtom) : reportFail(testAtom);
  }

  Severity getReportableSeverity() const { return mReportableSeverity; }

private:
  //!
  //! \brief returns an appropriate string for prefixing a log message with the given severity
  //!
  static const char * severityPrefix(Severity severity)
  {
    switch (severity) {
      case Severity::kINTERNAL_ERROR:
        return "[F] ";
      case Severity::kERROR:
        return "[E] ";
      case Severity::kWARNING:
        return "[W] ";
      case Severity::kINFO:
        return "[I] ";
      case Severity::kVERBOSE:
        return "[V] ";
      default:
        assert(0);
        return "";
    }
  }

  //!
  //! \brief returns an appropriate string for prefixing a test result message with the given result
  //!
  static const char * testResultString(TestResult result)
  {
    switch (result) {
      case TestResult::kRUNNING:
        return "RUNNING";
      case TestResult::kPASSED:
        return "PASSED";
      case TestResult::kFAILED:
        return "FAILED";
      case TestResult::kWAIVED:
        return "WAIVED";
      default:
        assert(0);
        return "";
    }
  }

  //!
  //! \brief returns an appropriate output stream (cout or cerr) to use with the given severity
  //!
  static std::ostream & severityOstream(Severity severity)
  {
    return severity >= Severity::kINFO ? std::cout : std::cerr;
  }

  //!
  //! \brief method that implements logging test results
  //!
  static void reportTestResult(const TestAtom & testAtom, TestResult result)
  {
    severityOstream(Severity::kINFO) << "&&&& " << testResultString(result) << " " << testAtom.mName
                                     << " # " << testAtom.mCmdline << std::endl;
  }

  //!
  //! \brief generate a command line string from the given (argc, argv) values
  //!
  static std::string genCmdlineString(int argc, char const * const * argv)
  {
    std::stringstream ss;
    for (int i = 0; i < argc; i++) {
      if (i > 0) ss << " ";
      ss << argv[i];
    }
    return ss.str();
  }

  Severity mReportableSeverity;
};

namespace
{

//!
//! \brief produces a LogStreamConsumer object that can be used to log messages of severity kVERBOSE
//!
//! Example usage:
//!
//!     LOG_VERBOSE(logger) << "hello world" << std::endl;
//!
inline LogStreamConsumer LOG_VERBOSE(const Logger & logger)
{
  return LogStreamConsumer(logger.getReportableSeverity(), Severity::kVERBOSE);
}

//!
//! \brief produces a LogStreamConsumer object that can be used to log messages of severity kINFO
//!
//! Example usage:
//!
//!     LOG_INFO(logger) << "hello world" << std::endl;
//!
inline LogStreamConsumer LOG_INFO(const Logger & logger)
{
  return LogStreamConsumer(logger.getReportableSeverity(), Severity::kINFO);
}

//!
//! \brief produces a LogStreamConsumer object that can be used to log messages of severity kWARNING
//!
//! Example usage:
//!
//!     LOG_WARN(logger) << "hello world" << std::endl;
//!
inline LogStreamConsumer LOG_WARN(const Logger & logger)
{
  return LogStreamConsumer(logger.getReportableSeverity(), Severity::kWARNING);
}

//!
//! \brief produces a LogStreamConsumer object that can be used to log messages of severity kERROR
//!
//! Example usage:
//!
//!     LOG_ERROR(logger) << "hello world" << std::endl;
//!
inline LogStreamConsumer LOG_ERROR(const Logger & logger)
{
  return LogStreamConsumer(logger.getReportableSeverity(), Severity::kERROR);
}

//!
//! \brief produces a LogStreamConsumer object that can be used to log messages of severity
//! kINTERNAL_ERROR
//         ("fatal" severity)
//!
//! Example usage:
//!
//!     LOG_FATAL(logger) << "hello world" << std::endl;
//!
inline LogStreamConsumer LOG_FATAL(const Logger & logger)
{
  return LogStreamConsumer(logger.getReportableSeverity(), Severity::kINTERNAL_ERROR);
}

}  // anonymous namespace
}  // namespace tensorrt_common

#endif  // TENSORRT_COMMON__LOGGER_HPP_
